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离子液体界面修饰的高效稳定FAPbI3钙钛矿太阳能电池

Yameen Ahmed1,5, 封想想1, 高远基1, 丁洋1, 龙操玉1, Mustafa Haider1, 李恒月1, 李专2, 黄誓成3,4, Makhsud I. Saidaminov5,6, 阳军亮1,2   

  1. 1 中南大学物理与电子学院, 超微结构与超快过程湖南省重点实验室, 长沙 410083;
    2 中南大学粉末冶金国家重点实验室, 长沙 410083;
    3 广西晶联光电材料有限公司, 广西柳州 545036;
    4 中南大学材料科学与工程学院, 长沙 410083;
    5 Department of Electrical & Computer Engineering, University of Victoria, 3800 Finnerty Road, Victoria, British Columbia V8P 5C2, Canada.;
    6 Department of Chemistry, University of Victoria, 3800 Finnerty Road, Victoria, British Columbia V8P 5C2, Canada
  • 收稿日期:2023-03-31 修回日期:2023-05-23 录用日期:2023-05-24 发布日期:2023-05-31
  • 通讯作者: 李恒月, 阳军亮 E-mail:hengyueli@csu.edu.cn;junliang.yang@csu.edu.cn
  • 基金资助:
    国家重点研发计划(2022YFB3803300), 国家自然科学基金(51673214, 52203250), 中南大学高性能计算中心及中南大学粉末冶金国家重点实验室资助 项目

Interface Modification by Ionic Liquid for Efficient and Stable FAPbI3 Perovskite Solar Cells

Yameen Ahmed1,5, Xiangxiang Feng1, Yuanji Gao1, Yang Ding1, Caoyu Long1, Mustafa Haider1, Hengyue Li1, Zhuan Li2, Shicheng Huang3,4, Makhsud I. Saidaminov5,6, Junliang Yang1,2   

  1. 1 Hunan Key Laboratory for Super-microstructure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha 410083, China;
    2 State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
    3 Guangxi Crystal Union Photoelectric Materials Co., Ltd., Liuzhou 545036, Guangxi Zhuang Autonomous Region, China;
    4 School of Materials Science and Engineering, Central South University, Changsha 410083, China;
    5 Department of Electrical&Computer Engineering, University of Victoria, 3800 Finnerty Road, Victoria, British Columbia V8P 5C2, Canada;
    6 Department of Chemistry, University of Victoria, 3800 Finnerty Road, Victoria, British Columbia V8P 5C2, Canada
  • Received:2023-03-31 Revised:2023-05-23 Accepted:2023-05-24 Published:2023-05-31
  • Contact: Hengyue Li, Junliang Yang E-mail:hengyueli@csu.edu.cn;junliang.yang@csu.edu.cn
  • Supported by:
    The project was supported by the National Key Research and Development Program of China (2022YFB3803300), the National Natural Science Foundation of China (51673214, 52203250), the High Performance Computing Center of Central South University, and the State Key Laboratory of Powder Metallurgy, Central South University, China.

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摘要： 碘铅甲眯(FAPbI3)钙钛矿太阳能电池因其优异的光伏性能而受到广泛关注，但器件的长期稳定性仍然是FAPbI3太阳能电池的关键问题。FAPbI3黑色钙钛矿相在室温下会相变为黄色非钙钛矿相，且水分会加速这一相变。界面工程是提高钙钛矿太阳能电池稳定性的常用方法之一。作为绿色溶剂，离子液体被认为是有毒界面修饰剂的潜在替代品，这也提高了它们的商业可行性，并加速了它们在可再生能源市场的应用。本研究利用具有低挥发性、低毒性、高导电性和高热稳定性的离子液体1-乙基-3-甲基咪唑四氟硼酸盐(EMIM[BF4])来修饰钙钛矿太阳能电池的电子传输层和钙钛矿层之间的界面。离子液体的引入不仅减少了界面缺陷，而且提高了钙钛矿薄膜的质量。密度泛函理论计算表明，离子液体与钙钛矿表面之间存在较强的界面相互作用，有利于降低钙钛矿表面缺陷态密度，稳定钙钛矿晶格。除钙钛矿薄膜缺陷外，溶液处理的SnO2也存在表面缺陷。在SnO2表面的缺陷产生缺陷态，也会导致能带对准问题和稳定性问题。密度泛函理论计算表明，有离子液体的表面间隙态比没有离子液体的表面间隙态小，这种减弱的表面间隙态表明表面区域载流子复合减少，有利于提高器件性能。因此，我们实现了功率转换效率大于22%的离子液体修饰的FAPbI3钙钛矿太阳能电池(对照21%)。在相对湿度~20%的干箱中存放1800 h以上后，冠军器件保留了初始状态的~90%，而控制器件降解为非钙钛矿黄色六方相(δ-FAPbI3)。

关键词: FAPbI3, 相稳定性, SnO2, 钙钛矿太阳能电池, 离子液体, 界面工程

Abstract: Formamidinium lead iodide (FAPbI3) perovskite solar cells (PSCs) have attracted significant attention owing to their outstanding optoelectronic properties, but long-term device stability is still a crucial issue related to FAPbI3 PSCs. FAPbI3 undergoes phase transition from black perovskite phase to yellow non-perovskite phase at room temperature, and moisture triggers this phase transition. One of the most widely used methods to improve the stability of PSCs is interface engineering. Being green functional solvents, ionic liquids (ILs) have been regarded as potential alternatives to toxic interface modifiers, thereby increasing their commercial viability and accelerating their adoption in the renewable energy market. In this study, an IL, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM[BF4]) was used to modify the interface between the electron transport layer and perovskite layer due to its low volatility, low toxicity, high conductivity, and high thermal stability. The introduction of IL not only reduces interface defects but also improves perovskite film quality. Density functional theory (DFT) calculations show that there is a strong interface interaction between the IL and perovskite surface that is beneficial to decrease the density of defect states of the perovskite surface and stabilize the perovskite lattice. Apart from the defects in the perovskite film, solution-processed SnO2 also suffers from surface imperfections. Defects on the SnO2 surface generate defect states, which cause band alignment issues and stability issues. DFT calculations show that the surface gap states with IL are smaller than those without IL. Such weakened surface gap states indicate reduced carrier recombination at the surface region, which improves the device performance. Consequently, we achieved a power conversion efficiency exceeding 22% for the IL-modified FAPbI3 PSCs (control ~21%). After storing for over 1800 h in a dry box (relative humidity (RH) ~20%), the champion device retained ~90% of its initial efficiency, while the control devices degraded into non-perovskite yellow hexagonal phase (δ-FAPbI3).

Key words: FAPbI3, Phase stability, SnO2, Perovskite solar cells, Ionic liquid, Interface engineering